28. Analyze the graph of the growth curve representing the human population of Ireland before 1900 (Figure 2). (a) Label the different phases of this growth curve. (b) Suggest possible reasons for the decline in car- rying capacity at time D. (c) Research the events that actually occurred in Ireland before 1900 that led to this decline in car- that are carrying the bacteria Borrelia burgdorferi. Today, the only area in Ontario with a risk of Lyme dis- ease is Long Point on the shore of Lake Erie. Research Lyme disease and answer the following: (a) Is Lyme disease a serious health concern? Justify your answer. (b) Is there a natural balance between predators and the deer population of Long Point? (c) What strategies in both wildlife management and human behaviour might reduce the risk of acquiring this disease? GO rying capacity. GO www.science.nelson.com initial carrying сарacity www.science.nelson.com 31. Some suggest that lakes without fish populations due to acid deposition can simply be stocked with young fish. (a) Who might be satisfied with this solution? Explain. (b) Explain why this action does not solve the problem. new carrying сарacity 32. Great gray owls, Strix nebulosa, are very vulnerable to human disturbance such as clearing of forests for timber or farmland. Their population dispersion and geographic range are most affected by the availability of nest sites. Other factors such as food supply, influ- ence the carrying capacity of the local environment. These birds are top predators and feed heavily of mice and voles. A D. Time Figure 2 29. Examine the data in the table below which compares Canadian population statistics for the periods 1861–1871 and 1991-1996. (a) How might use of pesticides influence the health of gray owl populations? (b) How could forestry practices be altered to limit negative impacts on the range and dispersion patterns of these owls? (c) Many environmental organizations advocate taking action to ensure this and similar wildlife populations are given adequate protection. What reasons do you think these groups would offer in support of their position? Explain. 33. As water becomes scarce, the competition for water between cities and countryside intensifies. In this competition, farmers almost always lose. The demands for water use by people in cities must by balanced by the needs for water used for irrigation. (a) What water uses would you consider essential for city dwellers? (b) Outline several changes in lifestyle and/or tech- nologies that could be used to reduce water demand in homes and industries. (c) How might farmers reduce their water demands? Table 3 Canadian Population Statistics Population Births at end of Deaths (1000's) Immigrants Emigrants (1000's) (1000's) (1000's) period (1000's) 1861-1871 3 689 1 370 760 260 410 1991-1996 29 672 1 936 1 024 1 137 229 (a) What was Canada's annual per capita birth and death rates in the period from 1861–1871? (b) How did these values change during the next 130 years? Suggest reasons for these changes. (c) Calculate the annual percent growth rate for these two time intervals. Making Connections 30. Healthy, natural ecosystems play an important role in controlling the emergence and spread of infectious dis- eases by maintaining a balance between predators and prey, and parasites and their hosts. The deer tick, Ixodes dammini, feeds on white-tailed deer and occasionally Concid. Number of Individuals